Structural Engineering of Advanced Cathode Materials for Aqueous Zinc-ion Batteries
[eng] Aqueous zinc ion batteries (AZIBs) have garnered significant research attention due to their remarkably high-volume energy density, reaching up to 5,851 mAh mL-1. This surpasses the capabilities of state-of-the-art lithium-ion batteries (LIBs), making AZIBs a promising candidate for advanced e...
| Autor: | |
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2024 |
| País: | España |
| Institución: | Universidad de Barcelona |
| Repositorio: | Dipòsit Digital de la UB |
| OAI Identifier: | oai:diposit.ub.edu:2445/214733 |
| Acceso en línea: | https://hdl.handle.net/2445/214733 http://hdl.handle.net/10803/691939 |
| Access Level: | acceso abierto |
| Palabra clave: | Electroquímica Cinètica química Aigua Conversió directa de l'energia Electrochemistry Chemical kinetics Water Direct energy conversion |
| Sumario: | [eng] Aqueous zinc ion batteries (AZIBs) have garnered significant research attention due to their remarkably high-volume energy density, reaching up to 5,851 mAh mL-1. This surpasses the capabilities of state-of-the-art lithium-ion batteries (LIBs), making AZIBs a promising candidate for advanced energy storage technology. Additionally, the natural abundance, low cost, and non-toxic nature of zinc offer economic advantages and environmental sustainability, particularly beneficial for large-scale applications. One notable advantage of AZIBs is their ability to be fabricated in an air atmospheric environment, thanks to the air stability of the AZIBs system. This characteristic significantly simplifies the fabrication process, further enhancing the attractiveness of AZIBs for widespread adoption. However, the practical implementation of AZIBs still suffers from several intractable technical challenges, such as limited energy density and inadequate cycle life, which seriously hinder this technology from yielding practically viable energy density and cyclability. Selecting appropriate cathode materials and implementing rational structural design engineering can effectively overcome the aforementioned challenges. In Chapter 1, I summarize the state of the art on advanced cathode materials for AZIBs and particularly detail structural engineering strategies to achieve high energy density and extended cycle life. In Chapter 2, I detail my work on the design and engineering of K+ pre-intercalated MnO2 nanorods (K-MnO2-NR) as an efficient cathode to overcome the limitations of AZIBs. The K-MnO2-NR is synthesized by a facile one-step chemical method with a size of less than 10 nm. Their unique structure provides a large surface area, abundant active sites for ion storage, and a short diffusion path for ion transport. The intercalation of K+ also improves the conductivity of the electrode and stabilizes the tunnel structure. Consequently, this K-MnO2-NR configuration delivers a high capacity of 285 mAh g-1 at 0.1 A g-1, while retaining 222 mAh g-1 at 2 A g-1. Kinetic reaction analysis reveals that even under high charging/discharging rates, ion diffusion-controlled capacity plays a crucial role, which is beneficial for achieving high capacity under such conditions. Assembled pouch cells with K-MnO2-NR also exhibit promising application prospects. This work has been accepted for publication in the journal Ceramics International and it is already available online (https://doi.org/10.1016/j.ceramint.2024.04.324). However, the capacity of the enhanced MnO2 still falls short of expectations, hampering its practical application. The primary reason for this limitation is that the prepared crystalline MnO2 possess few defects, resulting in a reduced ion storage capacity. Hence, there arises a necessity to devise a novel defect engineering methodology to address this issue and obtain materials with high-density active sites, thereby enhancing their performance. In Chapter 3, to further improve MnO2-based cathodes, I introduce a method to obtain manganese oxide materials with high-density active sites through the in situ phase transformation of MnSe, thereby regulating the defect structure. I detail my work on the structural engineering of reduced graphene oxide (rGO)-coated MnSe nanoparticles (MnSe@rGO) as a cathode material for AZIBs. The introduction of rGO provides a surface-confining effect against morphological evolution, thus preventing structural failure of the electrode. Furthermore, the intrinsically high electronic conductivity of rGO facilitates the MnSe phase transition, enabling the utilization of its full capacity potential. The optimized MnSe@rGO-3 cathode demonstrates a significant specific capacity of 290 mAh g-1 at 0.1C and retains a specific capacity of 178 mAh g-1 even at 5C. Through quantitative electrochemical analyses, first-principles calculations, and in situ characterization, the enhanced capacitive zinc-ion storage behavior and phase transformation mechanism of MnSe@rGO cathode materials are elucidated. Moreover, the mechanical stability of rGO ensures the successful electrohydrodynamic (EHD) jet printing of flexible ZIBs into a flexible integrated functional system. As an illustration, a flexible touch-controlled light-emitting diode (LED) array system incorporating as-fabricated MnSe@rGO-3-based ZIBs is developed. This approach showcases effective performance in both flat and bent configurations, offering the added advantages of enhanced safety and environmental sustainability. This work was published in ACS Nano in 2023 (https://doi.org/10.1021/acsnano.3c00672). Despite the significant strides made in enhancing the specific capacity of Mn-based cathode materials through defect engineering, the persisting limitations associated with manganese dissolution and moderate cycle life continue to raise concerns. These issues indeed cast doubt on their viability for high-energy-density applications, particularly in application fields like wearables. In Chapter 4, to increase the energy density of AZIBs, I explain my work on the development of a new cathode material based on a layered metal chalcogenide (LMC), bismuth telluride (Bi2Te3) nanodisks, coated with polypyrrole (PPy) as cathode material for aqueous ZIBs, and then explore its storage mechanism. In situ X-ray diffraction (XRD) analysis, X-ray photoelectron spectroscopy (XPS) measurements, and density functional theory (DFT) calculations are employed to elucidate that the energy storage mechanism of Bi2Te3 is the insertion/extraction of protons rather than Zn ions within the (0 0 6) interlayers, coupled with the formation/deposition of Zn4SO4(OH)6·5H2O on the electrode surface. The PPy coating enhances the ionic conductivity of the LMC while preventing surface oxidation. Consequently, the Bi2Te3@PPy cathode exhibits remarkable rate performance and long-term cycling stability with ultra-long lifespans of over 5,000 cycles. They also present outstanding stability even under bending. This work was published in Advanced Materials in 2023 (https://doi.org/10.1002/adma.202305128). Finally, the main conclusions of this thesis, including a comparison chart of the three cathode materials developed in the thesis, and some perspectives for future work are presented. |
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